<<<<<<< HEAD Fenestrated EVAR in Greater Glasgow & Clyde

1 Timeline of data



2 Patients

2.1 Sex

  • Patient’s sex is show on the following column chart:


2.2 Age

  • Patient ages varies from 60 to 85 years old with the distribution shown on the following histogram:


  • These data look normally distributed but this can be tested by Shapiro Wilk normality test with the null hypothesis that the age data are normally distributed. p = 0.49.
  • Data are therefore best summarised with mean and standard deviation:
Characteristic Value (years)
Mean age 74
Standard deviation 5

2.3 Health Board

  • Not all fEVAR are for Greater Glasgow & Clyde health board patients.
  • Since 2019, Greater Glasgow & Clyde health board has taken over the vascular services of Forth Valley health board.
  • The patient’s health board are shown on the following column chart:


3 Aneurysms

3.1 Screening

  • Excluding women (who are not offered screening) and the fenestrated cuffs placed within existing EVARs, the numbers of screened versus non-screened aneurysms treated by fEVAR are shown below:


3.2 Size

  • Treated aneurysm size varies from 40 mm (in a patient with a common iliac artery at treatment threshold and AAA below treatment threshold) to 86 mm, as shown on the following histogram:


  • These data look possibly normally distributed but this can be tested by Shapiro Wilk normality test with the null hypothesis that the age data are normally distributed. p = 0 (ie. they are abnormally distributed)
  • Data are therefore best summarised with median and interquartile range:
Characteristic Value (mm)
Median size 58
Interquartile range 57 - 62

4 Investigations after aneurysm reaches treatment threshold size

4.1 Time to CT

  • Time to CT is defined as the time between imaging showing the aneurysm to have reached treatment threshold until the planning CT angiogram.
  • In 8 cases, a CT suitable for planning was the investigation which showed the aneurysm to be at threshold and so time to CT was 0 days.
  • These cases are therefore excluded from the following.
  • Time to CT is shown on the following histogram:


  • These look abnormally distributed.
  • Comparison of time to CT between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look different and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have CTA.
  • p = 0.05 - the alternative hypothesis can be accepted.

4.2 Time to ECHO

  • 4 patients did not have a documented echocardiogram.
  • 6 patients had ECHO prior to their imaging reaching treatment threshold size and did not have it repeated prior to fEVAR.
  • That leaves 51 patients who had ECHO after reaching treatments threshold.
  • The distribution of time to ECHO is shown in the following histogram:


  • These look abnormally distributed.
  • Comparison of time to ECHO between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look similar and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have ECHO.
  • p = 0.1 - the null hypothesis that there is no difference in time to ECHO cannot be rejected.

4.3 Time to PFT

  • 8 patients did not have documented pulmonary function tests.
  • 6 patients had PFTs prior to their imaging reaching treatment threshold size and did not have it repeated prior to fEVAR.
  • That leaves 48 patients who had PFT after reaching treatments threshold.
  • The distribution of time to PFT is shown in the following histogram:


  • These look abnormally distributed.
  • Comparison of time to PFT between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look similar and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have PFT.
  • p = 0.2 - the null hypothesis that there is no difference in time to PFT cannot be rejected.

4.4 Time to MDT

  • 7 patients did not have documented MDT discussion.
  • 2 patients had MDT discussion prior to their imaging reaching treatment threshold size and did not have it repeated prior to fEVAR.
  • That leaves 53 patients who had MDT after reaching treatments threshold.
  • The distribution of time to MDT is shown in the following histogram:


  • These look abnormally distributed.
  • Comparison of time to MDT between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look similar and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have MDT.
  • p = 0.09 - the null hypothesis that there is no difference in time to MDT cannot be rejected.

4.5 Time to fEVAR

  • The distribution of time to fEVAR is shown in the following histogram:


  • These look abnormally distributed.
  • Median and IQR for time to fEVAR are shown below:
Characteristic Value (days)
Median time 222
Interquartile range 147.25 - 277.75

  • Comparison of time to fEVAR between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look similar and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have fEVAR.
  • p = 0.35 - the null hypothesis that there is no difference in time to fEVAR cannot be rejected.

4.6 Comparative timeline

  • The different time delays presented above can be shown together in a single boxplot:

  • It is visually apparent that CT imaging, ECHO, PFTs and MDT discussion are parallel investigations with none incurring a particular time penalty.
  • There is a subsequent delay to the procedure, some of which can be accounted for by the time taken to manufacture a custom stent-graft.

5 Procedural details

5.1 Technical

5.1.1 Device

  • The number of each type of stent-graft used are shown in the following chart:


  • However this chart hides the fact that the choice of stent-graft has changed over time, as shown below:


5.1.2 fEVAR type

  • The number of each type of fEVAR are shown in the folling chart:

  • t/fEVAR is a fEVAR with a separate thoracic stent-graft component.
  • b/fEVAR is a combined branch and fenestrated custom device.
  • bEVAR is an off-the-shelf branched device.

5.1.3 Planned fenestration numbers

  • The number of planned fenestrations and/or branchse are shown in the following chart:

5.1.4 Radiation

  • Radiation dose is presented below as dose area product, with three histograms each with colouring based on a separate factor, namely the device used, the type of fEVAR and the number of planned fenestrations:
## Warning: Removed 2 rows containing non-finite values (stat_bin).

## Warning: Removed 2 rows containing non-finite values (stat_bin).

## Warning: Removed 2 rows containing non-finite values (stat_bin).


  • From the above histograms, three fenestrated cuff procedures have resulted in two dose outliers.
  • They are therefore excluded from the summary statistics below.
  • Firstly, DAP distribution but this can be tested by Shapiro Wilk normality test with the null hypothesis that the DAP data are normally distributed. p = 0.18 (ie. they are normally distributed).
  • Summary DAP statistics are shown below:
Characteristic Value (Gy/cm^2)
Minimum DAP 2461
Maximum DAP 35892
Mean DAP* 16000
Standard deviation* 8000
  • *Mean and standard deviation have been rounded to the nearest thousand.

5.1.5 Access

  • Referring to the method of femoral access, the options are “cut-down”, which may or may not involve a conduit, “percutaneous”, which at this institution means two Proglides pre-inserted before the large sheath and “hybrid” in which one groin is accessed by each method.
  • The numbers are shown on the following chart:

  • ‘Hybrid’ means one femoral cut-down with percutaneous access on the other side.

  • Unsuccessful percutaneous access is defined as any situation in which surgical haemostasis was required on a groin that was accessed percutaneously.
  • The numbers are shown on the following chart:

  • Hybrid access cases are included in the above data.

  • Use of upper limb access, whether planned or un-planned, and whether used for cannulation of a fenestration or any other reason, is shown on the following chart:


5.2 Patient

5.2.1 ASA

  • Patient status has been collected as ASA only, and is shown below:


5.2.2 Anaesthetic

  • Method of anaesthesia used for fEVAR is shown below:


5.3 Hospital stay

  • Length of hospital stay varies from -4.4799^{4} days to 126 days with a median hospital stay of 4 days.
  • These are demonstrated on the following histogram:


5.4 Survival

  • Survival after fEVAR is shown below:


  • Survival split by fEVAR type is shown below:


5.5 Re-interventions

5.5.1 Number of re-interventions

  • 13 patients have had 20 re-interventions.
  • Re-intervention rate is 21%.
  • It is worth noting that re-intervention in fEVAR with a tEVAR component often involves a second procedure as either a limb or a fenestration is left incomplete during the index procedure to lower the risk of spinal cord ischaemia.

5.5.2 Re-intervention survival

  • Re-intervention survival is shown below:


  • Re-intervention survival split by fEVAR type is shown below:


======= Fenestrated EVAR in Greater Glasgow & Clyde

1 Timeline of data



2 Patients

2.1 Sex

  • Patient’s sex is show on the following column chart:


2.2 Age

  • Patient ages varies from 60 to 85 years old with the distribution shown on the following histogram:


  • These data look normally distributed but this can be tested by Shapiro Wilk normality test with the null hypothesis that the age data are normally distributed. p = 0.77.
  • Data are therefore best summarised with mean and standard deviation:
Characteristic Value (years)
Mean age 74
Standard deviation 5

2.3 Health Board

  • Not all fEVAR are for Greater Glasgow & Clyde health board patients.
  • Since 2019, Greater Glasgow & Clyde health board has taken over the vascular services of Forth Valley health board.
  • The patient’s health board are shown on the following column chart:


3 Aneurysms

3.1 Screening

  • Excluding women (who are not offered screening) and the fenestrated cuffs placed within existing EVARs, the numbers of screened versus non-screened aneurysms treated by fEVAR are shown below:


3.2 Size

  • Treated aneurysm size varies from 40 mm (in a patient with a common iliac artery at treatment threshold and AAA below treatment threshold) to 86 mm, as shown on the following histogram:


  • These data look possibly normally distributed but this can be tested by Shapiro Wilk normality test with the null hypothesis that the age data are normally distributed. p = 0 (ie. they are abnormally distributed)
  • Data are therefore best summarised with median and interquartile range:
Characteristic Value (mm)
Median size 58
Interquartile range 57 - 63.5

4 Investigations after aneurysm reaches treatment threshold size

4.1 Time to CT

  • Time to CT is defined as the time between imaging showing the aneurysm to have reached treatment threshold until the planning CT angiogram.
  • In 4 cases, a CT suitable for planning was the investigation which showed the aneurysm to be at threshold and so time to CT was 0 days.
  • These cases are therefore excluded from the following.
  • Time to CT is shown on the following histogram:


  • These look abnormally distributed.
  • Comparison of time to CT between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look different and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have CTA.
  • p = 0.03 - the alternative hypothesis can be accepted.

4.2 Time to ECHO

  • 3 patients did not have a documented echocardiogram.
  • 4 patients had ECHO prior to their imaging reaching treatment threshold size and did not have it repeated prior to fEVAR.
  • That leaves 39 patients who had ECHO after reaching treatments threshold.
  • The distribution of time to ECHO is shown in the following histogram:


  • These look abnormally distributed.
  • Comparison of time to ECHO between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look similar and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have ECHO.
  • p = 0.2 - the null hypothesis that there is no difference in time to ECHO cannot be rejected.

4.3 Time to PFT

  • 6 patients did not have documented pulmonary function tests.
  • 3 patients had PFTs prior to their imaging reaching treatment threshold size and did not have it repeated prior to fEVAR.
  • That leaves 38 patients who had PFT after reaching treatments threshold.
  • The distribution of time to PFT is shown in the following histogram:


  • These look abnormally distributed.
  • Comparison of time to PFT between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look similar and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have PFT.
  • p = 0.18 - the null hypothesis that there is no difference in time to PFT cannot be rejected.

4.4 Time to MDT

  • 7 patients did not have documented MDT discussion.
  • 1 patients had MDT discussion prior to their imaging reaching treatment threshold size and did not have it repeated prior to fEVAR.
  • That leaves 39 patients who had MDT after reaching treatments threshold.
  • The distribution of time to MDT is shown in the following histogram:


  • These look abnormally distributed.
  • Comparison of time to MDT between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look similar and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have MDT.
  • p = 0.11 - the null hypothesis that there is no difference in time to MDT cannot be rejected.

4.5 Time to fEVAR

  • The distribution of time to fEVAR is shown in the following histogram:


  • These look abnormally distributed.
  • Median and IQR for time to fEVAR are shown below:
Characteristic Value (days)
Median time 237
Interquartile range 154 - 306.5

  • Comparison of time to fEVAR between screened and non-screened patients can be visualised as a boxplot, given that boxplots display the median and IQR which are the appropriate measures for these data:


  • These look similar and this can be tested with a Mann Whitney U test to compare the groups with the alternative hypothesis that screened patients wait less time to have fEVAR.
  • p = 0.46 - the null hypothesis that there is no difference in time to fEVAR cannot be rejected.

4.6 Comparative timeline

  • The different time delays presented above can be shown together in a single boxplot:

  • It is visually apparent that CT imaging, ECHO, PFTs and MDT discussion are parallel investigations with none incurring a particular time penalty.
  • There is a subsequent delay to the procedure, some of which can be accounted for by the time taken to manufacture a custom stent-graft.

5 Procedural details

5.1 Technical

5.1.1 Device

  • The number of each type of stent-graft used are shown in the following chart:


  • However this chart hides the fact that the choice of stent-graft has changed over time, as shown below:


5.1.2 fEVAR type

  • The number of each type of fEVAR are shown in the folling chart:

  • t/fEVAR is a fEVAR with a separate thoracic stent-graft component.

5.1.3 Planned fenestration numbers

  • The number of planned fenestrations are shown in the following chart:

5.1.4 Radiation

  • Radiation dose is presented below as dose area product, with three histograms each with colouring based on a separate factor, namely the device used, the type of fEVAR and the number of planned fenestrations:


  • From the above histograms, three fenestrated cuff procedures have resulted in two dose outliers.
  • They are therefore excluded from the summary statistics below.
  • Firstly, DAP distribution but this can be tested by Shapiro Wilk normality test with the null hypothesis that the DAP data are normally distributed. p = 0.37 (ie. they are normally distributed).
  • Summary DAP statistics are shown below:
Characteristic Value (Gy/cm^2)
Minimum DAP 2461
Maximum DAP 35892
Mean DAP* 17000
Standard deviation* 8000
  • *Mean and standard deviation have been rounded to the nearest thousand.

5.1.5 Access

  • Referring to the method of femoral access, the options are “cut-down”, which may or may not involve a conduit, “percutaneous”, which at this institution means two Proglides pre-inserted before the large sheath and “hybrid” in which one groin is accessed by each method.
  • The numbers are shown on the following chart:

  • ‘Hybrid’ means one femoral cut-down with percutaneous access on the other side.

  • Unsuccessful percutaneous access is defined as any situation in which surgical haemostasis was required on a groin that was accessed percutaneously.
  • The numbers are shown on the following chart:

  • Hybrid access cases are included in the above data.

  • Use of upper limb access, whether planned or un-planned, and whether used for cannulation of a fenestration or any other reason, is shown on the following chart:


5.2 Patient

5.2.1 ASA

  • Patient status has been collected as ASA only, and is shown below:


5.2.2 Anaesthetic

  • Method of anaesthesia used for fEVAR is shown below:


5.3 Hospital stay

  • Length of hospital stay varies from 0 days to 67 days with a median hospital stay of 5 days.
  • These are demonstrated on the following histogram:


5.4 Survival

  • Survival after fEVAR is shown below:


  • Survival split by fEVAR type is shown below:


5.5 Re-interventions

5.5.1 Number of re-interventions

  • 8 patients have had 11 re-interventions.
  • Re-intervention rate is 16%.
  • It is worth noting that re-intervention in fEVAR with a tEVAR component often involves a second procedure as either a limb or a fenestration is left incomplete during the index procedure to lower the risk of spinal cord ischaemia.

5.5.2 Re-intervention survival

  • Re-intervention survival is shown below:


  • Re-intervention survival split by fEVAR type is shown below:


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